network: tcp_connect should return certain errors up the stack

The current tcp_connect code completely ignores errors from sending an skb.
This makes sense in many situations (like -ENOBUFFS) but I want to be able to
immediately fail connections if they are denied by the SELinux netfilter hook.
Netfilter does not normally return ECONNREFUSED when it drops a packet so we
respect that error code as a final and fatal error that can not be recovered.

Based-on-patch-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 05b1ecf36763..bb8f547fc7d2 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2592,6 +2592,7 @@ int tcp_connect(struct sock *sk)
 {
         struct tcp_sock *tp = tcp_sk(sk);
         struct sk_buff *buff;
+        int err;
 
         tcp_connect_init(sk);
 
@@ -2614,7 +2615,9 @@ int tcp_connect(struct sock *sk)
         sk->sk_wmem_queued += buff->truesize;
         sk_mem_charge(sk, buff->truesize);
         tp->packets_out += tcp_skb_pcount(buff);
-        tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
+        err = tcp_transmit_skb(sk, buff, 1, sk->sk_allocation);
+        if (err == -ECONNREFUSED)
+                return err;
 
         /* We change tp->snd_nxt after the tcp_transmit_skb() call
          * in order to make this packet get counted in tcpOutSegs.